Tape carrier package and method of fabricating the same

ABSTRACT

A tape carrier package with a widow that is capable of confirming an alignment extent between the tape carrier package and a print wiring board in bonding the tape carrier package mounted with an integrated circuit on the liquid crystal panel and the print wiring board. In the package, the integrated circuit is mounted onto a base film. Input pads are connected to the integrated circuit and formed on the base film. Dummy pads are formed at the left and right side thereof not to be connected to the integrated circuit. Windows are provided by opening the base film adjacent to the dummy pads to expose at least two of said dummy pads.

BACKGROUND OF THE INVENTION

[0001] This application claims benefit of Korean patent applicationnumber P2000-0866, filed Feb. 23, 2000, which is hereby incorporated byreference for all purposes as if fully set forth herein.

[0002] 1. Field of the Invention

[0003] This invention relates to a tape carrier package for mounting anintegrated circuit and a liquid crystal display containing the same, andmore particularly to a tape carrier package with a window through whichan alignment between the tape carrier package and a printed wiring boardcan be confirmed with the naked eye.

[0004] 2. Description of the Related Art

[0005] Generally, an active matrix liquid crystal display uses thin filmtransistors (TFTs) as switching devices to display a natural-lookingmoving picture. Since such a liquid crystal display device can be madeinto a smaller-size device than a cathode ray tube, it is commerciallyviable for use as a monitor such as a portable television or a lap-toppersonal computer or other consumer device.

[0006] The active matrix liquid crystal display displays a picturecorresponding to video signals such as television signals on a pixel (orpicture element) matrix having pixels arranged at each intersectionbetween gate lines and data lines. Each pixel includes a liquid crystalcell for controlling a transmitted light quantity in accordance with avoltage level of a data signal from a data line. A TFT (thin filmtransistor) is installed at an intersection between a gate line and adata line to switch a data signal to be transferred to the liquidcrystal cell in response to a scanning signal (i.e., a gate pulse) fromthe gate line.

[0007] Such a liquid crystal display requires a number of integratedcircuits (ICs) connected to the data lines and the gate lines to applydata signals and scanning signals to the data lines and the gate lines,respectively. The ICs are installed between the printed wiring board(PWB) and the liquid crystal panel to apply signals supplied from thePWB to the data lines and the gate lines. IC mounting methods includechip on board, hereinafter referred to as “COB”, tape automated bonding,hereinafter referred to as “TAB”, and chip on glass, hereinafterreferred to as “COG”. (Other methods are also possible). The COB systemis mainly used for a monochromatic liquid crystal display having a pixelpitch of more than 300 μm. As shown in FIG. 1, in this COB system, ICs 8are mounted on a PWB 6 and a heat-seal connector 10 connects the PWB 6and a glass substrate 3 in a liquid crystal panel 2. In this case, aback light unit 4 used as a light source is provided between the liquidcrystal panel 2 and the PWB 6. As shown in FIG. 2, in the TAB system,ICs 14 are mounted on a tape carrier package (TCP) 12. The TCP 12 isconnected between the PWB 6 and the liquid crystal panel 3. As shown inFIG. 3, in the COG system, an IC chip 20 is directly mounted on a glasssubstrate 17 in a liquid crystal panel 16.

[0008] The above-mentioned TAB IC mounting method has been widelyemployed because it can widen an effective area of the panel and has arelatively simple mounting process.

[0009] As shown in FIG. 4, the TCP 12 employed in the TAB systemincludes a base film 22 on which is mounted an IC 14. The base film 22is also provided with input and output pads 24 and 26 connected to inputand output pins of the IC 14. The input and output pads 24 and 26 arefixed with the base film 22 by an adhesive layer 16 coated on the rearsurface of the base film 22. The input and output pads 24 and 26 have atwo-layer structure in which copper(Cu) is plated with tin(Sn) forpreventing oxidation. As shown in FIG. 5A, the input pads 24 of the basefilm 22 are connected, via an anisotropic conductive film (ACF) 28, topads 32 on a PWB 34. Likewise, the output pads 26 of the base film 22are connected, via the ACF 30, to data/gate pads on the liquid crystalpanel 2.

[0010]FIG. 5A and FIG. 5B illustrate a process of adhering the TCP tothe PWB with the ACF 28. The input pads 24 are adhered to the bare film22 by a bonding layer 16 coated on the base film 22. Conductiveparticles are coated on the ACF 28. The TCP 12 and the PWB 34 areadhered to each other by applying a certain pressure at a desiredtemperature after the ACF 28 has been coated. As shown in FIG. 5B, theconductive particles 30 coated on the ACF 28 are connected between theinput pads 24 and a wiring 32 of the PWB 34 after the adhesion of theTCP 12 to the PWB 34 to form a current path.

[0011] Because the base film 22 has a low light transmissivity whichadhered to the PWB, it is impossible to confirm an alignment statebetween the input pads and the wiring of the PWB. Accordingly,significantly bad alignments may be produced in the process of adheringthe TCP to the PWB. Also, since the liquid crystal panel made from aglass transmits light even after the adhesion of the TCP to the PWB,alignment can be confirmed using a microscope; whereas, since the PWBdoes not transmit light, alignment cannot be confirmed using amicroscope. Thus, a strong light is irradiated onto the base film todetermine an alignment extent by a light reflected from the input pads.However, this method is complicated and unable to accurately determinean alignment. Also, such a method is time consuming.

SUMMARY OF THE INVENTION

[0012] Accordingly, it is an object of the present invention to providea tape carrier package with a window for confirming an alignment extentwith the naked eye and a liquid crystal display device containing thepackage, and an adhering method thereof.

[0013] In order to achieve these and other objects of the invention, atape carrier package according to one aspect of the present inventionincludes a base film; an integrated circuit mounted on the base film;input pads connected to the integrated circuit to be formed on the basefilm; dummy pads formed at the side end of the input pads; and windowsprovided by removing the base film adjacent to the dummy pads into adesired size to expose at least two of said dummy pads.

[0014] A liquid crystal display device according to another aspect ofthe present invention comprises a liquid crystal panel; a printed wiringboard including an output wiring for receiving image signals from theexterior thereof to output them to the liquid crystal panel, and a dummywiring provided at the side ends of the output wiring; and a tapecarrier package including input pads opposed to the output wiring of theprinted wiring board, output pads corresponding to signal pads of theliquid crystal panel, dummy pads opposed to the dummy wiring of theprinted wiring board at the side ends of the input pads, and windowsdefined by opening the base film to expose at least two of said dummypads, said tape carrier package being adhered, via the input pad and thedummy pads, to the print wiring board and, via the output pads, to theliquid crystal panel.

[0015] In some embodiments of the invention, dummy pads are included onthe printed wiring board and TCP. The dummy pads are exposed by thewindow in the tape carrier package to confirm alignment of the tapecarrier package to the PWB. In other embodiments, no dummy pads areprovided in the PWB/TCP. In these embodiments, only a portion of thesignal pads are exposed by the window. Some or all of the pads on theTCP/PWB may be lengthened to compensate for portions exposed by thewindow. Of course, this arrangement can also be used even when dummypads are present.

[0016] A method of jointly adhering a tape carrier package of a liquidcrystal display device according to still another aspect of the presentinvention includes the steps of adhering input pads and dummy pads ofthe tape carrier package to a wiring of a printed wiring board tocorrespond to each other with an isotropic conductive film therebetween;and confirming an alignment of the dummy pads to the print wiring boardwith the aid of the windows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and other objects of the invention will be apparent fromthe following detailed description of preferred embodiments of thepresent invention with reference to the accompanying drawings, in which:

[0018]FIG. 1 is a sectional view showing an integrated circuit mountingmethod employing the conventional chip on board system;

[0019]FIG. 2 is a sectional view showing an integrated circuit mountingmethod employing the conventional tape automated bonding system;

[0020]FIG. 3 is a sectional view showing a liquid crystal display deviceemploying the conventional chip on glass system;

[0021]FIG. 4 is a detailed perspective view showing the structure of thetape carrier package in FIG. 2;

[0022]FIG. 5A and FIG. 5B are plan views showing a process of adheringthe tape carrier package to the printed wiring board shown in FIG. 4;

[0023]FIG. 6 is a detailed perspective view showing the configuration ofa tape carrier package according to the present invention; and

[0024]FIG. 7A and FIG. 7B are sectional views showing a process ofadhering the tape carrier package to the printed wiring board shown inFIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Referring to FIG. 6, there is shown a tape carrier package (TCP)according to an embodiment of the present invention. The TCP 40 includesa base film 42, ICs 44 mounted on the base film 42, input and outputpads 48 and 50 connected to the input and output pins of the ICs 44 andformed on the base film 42, dummy pads 46 provided at the side end ofthe input pads 48, and windows 54 defined by openings in the base film42 to confirm an alignment of the dummy pads 46. The input and outputpads 48 and 50 have a two-layer structure in which copper(Cu) is platedwith tin(Sn) for preventing oxidation, and are fixed onto the base film42 with a bonding layer. For example, the dummy pads 46 are formed fiveby five at the left and right side of the input pads 48. The windows 54are formed into a square shape by punching the base film 42 providedwith the dummy pads 46. The windows 54 are punched into such a desiredsize that alignment between the first two or three dummy lines 46 can beconfirmed with the naked eye. The dummy pads 46 that are provided withthe window 54 prevent an alien substance from coming into contact withthe input pads 48. As shown in FIG. 7A, the input pads 48 fixed onto thebase film 42 are connected to the signal wiring 64 on the PWB 60 withthe aid of the ACF 56. Likewise, the output pads 50 of the base film 42are connected to data and gate pads on the liquid crystal panel with theaid of the ACF 56.

[0026]FIG. 7A and FIG. 7B show a process of adhering the TCP to the PWB.Referring to FIG. 7A and FIG. 7B, there is shown the ACF 56 for adheringthe TCP 40 to the PWB 60. The PWB 60 is provided with the dummy wiring58 corresponding to the dummy pads 46 formed at the TCP 40. The inputpads 48 and the dummy lines 46 of the TCP 40 are provided after thewindows 54 are formed on the base film 42.

[0027] Hereinafter, an adhesion process of the liquid crystal using thetape carrier package will be described in detail. After the ACF 56 hasbeen coated on the PWB 60, the TCP 40 is jointly adhered to the PWB 60as shown in FIG. 7B by applying a certain pressure thereto at a desiredtemperature. Since the conductive particles 62 contained in the ACF 56between the input pads 48 and the dummy pads 46 of the TCP 40 andbetween the wiring 64 and the dummy wiring 58 of the PWB 60 have anincreased density caused by the pressure, they connect the input pads 48to the wiring 64 of the PWB 60 electrically. In this case, an alignmentof the dummy pads 46 and the dummy wiring 58 is confirmed by means ofthe windows to check alignment errors.

[0028] As described above, according to the present invention, a desiredsize of windows are formed on the base film to confirm an alignmentstate between the tape carrier package and the print wiring board.Accordingly, the time required to check for misalignment can bedramatically shortened.

[0029] Although the present invention has been described in connectionwith the embodiments shown in the drawings described above, it should beunderstood by a person of ordinary skill in the art that the inventionis not limited to these embodiments, but rather that various changes ormodifications thereof are possible without departing from the spirit ofthe invention. Accordingly, the scope of the invention shall bedetermined only by the appended claims and their equivalents.

What is claimed is:
 1. A tape carrier package, comprising: a base film;an integrated circuit mounted on the base film; input pads connected tothe integrated circuit formed on the base film; and dummy pads formed ata side of the input pads; wherein the base film has a window formedtherein to expose at least one of said dummy pads.
 2. The tape carrierpackage according to claim 1, wherein said dummy pads include a firstdummy pad positioned between the input pads and the window, and a seconddummy pad positioned under the window.
 3. The tape carrier packageaccording to claim 1, wherein said dummy pads are not connected to theintegrated circuit.
 4. The tape carrier package according to claim 1,wherein said dummy pads are formed at two sides of the input pads.
 5. Amethod of jointly adhering a print wiring board to a tape carrierpackage including input pads on a base film, at least one dummy padformed at a side of the input pads, and a window for exposing a portionthe at least one dummy pad, said method comprising the steps of:adhering the input pads and the at least one dummy pad of the tapecarrier package to a wiring of the print wiring board to correspond toeach other with an isotropic conductive film therebetween; andconfirming an alignment of the at least one dummy pad to a dummy pad onthe printed wiring board with the aid of the window.
 6. A liquid crystaldisplay comprising; a liquid crystal panel a tape carrier packageconnected to the panel; and a printer wiring board connected to the tapecarrier package; the printed wiring board including a plurality of padswherein the tape carrier package includes a base film having a pluralityof pads formed thereon and at least one window formed therein such thatat least one portion of the at least one pad is exposed through thewindow such that an alignment of the at least one pad and acorresponding pad on the printed circuit board can be confirmed throughthe window.